Electronic control device

ABSTRACT

An internal power circuit lowers a battery voltage supplied always from an external side to generate a standby power voltage. A timer continues to measure an elapse of time in a standby state, after a main relay is turned off and supply of a power voltage is interrupted. A measured time data of the timer is saved to a save register during a time measurement operation of the timer. When a stop condition for stopping the time measurement operation of the timer is satisfied, a control circuit stops the operation of the internal power circuit. When the main relay is turned on, the internal power circuit is activated to start its operation again by the control circuit so that the measured time data saved to the save register is restored to the timer.

CROSS REFERENCE TO RELATED APPLICATION

This application is based on and incorporates herein by referenceJapanese patent application No. 2012-21806 filed on Feb. 3, 2012.

TECHNICAL FIELD

The present disclosure relates to an electronic control device, which issupplied with a first power voltage always from an external side and hasa circuit part supplied with the first power voltage as a second powervoltage through a power switch and operable even when the power switchis turned off.

In an electronic control apparatus for controlling an engine of avehicle, for example, various electronic circuits including amicrocomputer as a main circuit are provided as a control part, whichperforms various processing and operations for engine control. Thecontrol apparatus operates with electric power while an ignition switchas a power switch is being turned on. In this control apparatus, it isdesired to measure a soak time indicating an elapse of time from a timepoint, at which the power voltage to the control apparatus issubstantially shut off.

For example, the measured soak time is used in heat management control,which changes over control modes at a next engine start time. The heatmanagement control is provided to start the engine after warming up thecoolant of the engine thereby to reduce fuel consumption at the enginestart time for improved fuel economy and meet the exhaust emissionregulation. In this case, fall of the coolant temperature after theignition switch is turned off need be estimated and hence the soak timeneed be measured. The soak time also need be measured to perform a leakhole check (EVP leak check) to meet EVPOBD (California exhaust emissionregulation), which is designed to check a leak in EVP (evaporatorsystem) connecting a tank, a canister and a surge tank by operating thecontrol apparatus during the soak time.

JP 2003-315474A discloses that a host microcomputer calculates a soaktime based on a count value counted up by a soak timer. The soak timerselectively changes over a count-up time interval among predeterminedplural count-up time intervals based on a set code included in a commandsignal outputted from the host microcomputer when an ignition switch(IGSW) is turned off. An integrated circuit (IC) part including the soaktimer is operated with a power voltage (sub-power voltage), which issupplied when the microcomputer is turned to be in a stand-by state.

With recent advanced semiconductor process micronization technology,internal circuits of the IC are micro-structured and an operating powervoltage for the internal circuits is lowered. For the IC havingcircuits, which need be operable in the standby state, the power voltagefor the standby system need be differentiated for I/O circuits and otherinternal circuits. A power circuit (regulator) is thus additionallyneeded for providing a power voltage lowered for the internal circuits.Addition of the power circuit adds power consumption.

SUMMARY

It is therefore an object to provide an electronic control device, whichis capable of suppressing an increase of power consumption even in acase that a circuit operating in a standby state is provided.

According to one aspect, an electronic control device includes aninternal power circuit, a control circuit, a timer and a data memorycircuit. The internal power circuit is supplied with a first powervoltage always from an external side and a second power voltage througha power switch from the external side and generates a third powervoltage by lowering the first power voltage. The control circuitcontrols an operation of the internal power circuit. The timer issupplied with the third power voltage and measures at least a timeperiod of turn-off of the power switch. The data memory circuit issupplied with the first power voltage and stores data. While the timerperforms a time measuring operation after the power switch is turnedoff, the data memory circuit saves therein a measured time data of thetimer. When a stop condition for stopping the time measuring operationof the timer is satisfied, the control circuit stops an operation of theinternal power circuit. When the power switch is turned on, the controlcircuit starts the operation of the internal power circuit to restorethe measured time data saved in the data memory circuit to the timer.

BRIEF DESCRIPTION OF DRAWINGS

The above and other objects, features and advantages will become moreapparent from the following detailed description made with reference tothe accompanying drawings. In the drawings:

FIG. 1 is a functional block diagram showing an electric configurationof an electronic control unit according to one embodiment;

FIGS. 2A and 2B are a functional block diagram and a table showing aninternal configuration of a VOS3 regulator part shown in FIG. 1;

FIG. 3 is a functional block diagram showing an internal configurationof a soak timer part shown in FIG. 1;

FIG. 4 is a flowchart showing processing executed by the electroniccontrol unit when an ignition switch is turned on;

FIG. 5 is also a flowchart showing processing executed by the electroniccontrol unit when the ignition switch is turned off; and

FIG. 6 is a timing chart showing signal changes produced by theprocessing of FIG. 4 and FIG. 5 at various points.

DETAILED DESCRIPTION OF EMBODIMENT

Referring first to FIG. 1, one embodiment of an electronic controldevice, which is applied to an electronic control unit (ECU) 1 for avehicle, will be described in detail. The ECU 1 is provided to controlan engine mounted in a vehicle.

The ECU 1 has a battery terminal BATT and a main relay drive terminalJ2, which are directly connected to a positive terminal of a battery 2of the vehicle. A power terminal +B is also connected to the positiveterminal of the battery 2 through a normally-open contact 3C of a mainrelay 3, which is a power switch.

An IGSW terminal J1 is connected to the positive terminal of the battery2 through an ignition switch (IGSW) 4. A main relay drive terminal J3 isconnected to the other end of a coil 3L of the main relay 3, one end ofwhich is connected to the ground. The voltages supplied to the ECU 1through the battery terminal BATT and the power terminal +B are referredto as a battery voltage BATT (first power voltage) and a power voltage+B (second power voltage), respectively.

The ECU 1 includes a power circuit 5, a host microcomputer (hostcomputer as a high level control device) 6 and a relay controlintegrated circuit (IC) 7. The power circuit 5 receives the batteryvoltage BATT, the power voltage +B to generate and output four powervoltages VOM5, VOM1, VOS5 and VOS1. These four power voltages haverespective magnitudes as follows.

-   -   VOM5: main power voltage (5V) for the host computer I/O and the        relay control IC 7;    -   VOM1: main power voltage (1.2V) for a host computer core;    -   VOS5: standby power voltage (1.2V) for the relay control IC 7;        and    -   VOS1: standby power voltage (1.2V) for the host computer 6.

The standby power voltage VOS5 is the power voltage (first powervoltage) supplied always with the supply of the battery voltage BATT.The standby power voltage VOS1 is used to back up data of an internalRAM when the host computer 6 is in the standby state. The power circuit5 has a power-on reset function, which outputs a reset signal to thehost computer 6 from when the main power voltage VOM5 (second powervoltage) is outputted in response to supply of the power voltage +Buntil the power voltage is stabilized. The host computer 6 includes aCPU, a ROM, a RAM and the like (not shown) and executes various controlprograms for engine control in the known manner.

The relay control IC 7, which is an electronic control device, includesa communication circuit 8, a relay control circuit (activation circuit)9, a VOS3 regulator circuit 10, a soak timer circuit 11, and an inputcircuit 12. The communication circuit 8 performs serial communicationwith the host computer 6 and exchanges data with the soak timer circuit11. The relay control circuit 9 includes a three-input OR gate 13 and aN-channel MOSFET 14, and is supplied with the standby power voltageVOS5.

Input terminals of the OR gate 13 are connected to the output terminalof the host computer 6, the output terminal of the soak timer circuit 11and the IGSW terminal J1 through the input circuit 12. Although notshown, the IGSW terminal J1 is pulled down to the ground in the ECU 1through a resistor element. A source and a drain of the N-channel MOSFET14 are connected to main relay drive terminals J2 and J3. The inputcircuit 12 is formed of electronic components, which need no powervoltage. The input circuit 12 level-converts the power voltage of thebattery 2 inputted from the IGSW terminal J1 through the IGSW 4 to anIGSW signal, which has a level suitable to be inputted to the hostcomputer 6 and the OR gate 13.

The VOS3 regulator circuit 10 is configured as shown in FIG. 2A. TheVOS3 regulator circuit 10 includes a comparator 15, an OR gate 16, abandgap circuit 17 and a VOS3 regulator 18. The main power voltage VOM5is applied to a non-inverting input terminal of the comparator 15 and areference voltage VREF is applied to an inverting input terminal of thecomparator 15. An output terminal of the comparator 15 is connected toone of the input terminals of the OR gate 16. An oscillation enablesignal OE, which will be described later, is applied to the other of theinput terminals of the OR gate 16 from an oscillation control register24 built in the soak timer circuit 11. The comparator 15 and the OR gate16 form a control circuit 19. The bandgap circuit 17 and the VOS3regulator 18 form an internal power circuit 20.

The standby power voltage VOS5 is supplied to the bandgap circuit 17 andthe VOS3 regulator 18. The bandgap circuit 17 and the VOS3 regulator 18have enable terminals EN, respectively. An output terminal of the ORgate 16 is connected to the enable terminals EN. The bandgap circuit 17and the VOS3 regulator 18 become operative when the signal applied tothe enable terminals become high. Operations of the bandgap circuit 17and the VOS3 regulator 18 are shown in a table form in FIG. 28, in which“X” indicates an arbitrary value. The bandgap circuit 17 generates abandgap reference voltage of about 1.2V and outputs it to the VOS3regulator 18. The VOS3 regulator 18 generates a standby power voltageVOS3 (third power voltage) of 3V from the reference voltage and suppliesthe same to the soak timer circuit 11.

The soak timer circuit 11 is configured as shown in FIG. 3. The soaktimer circuit 11 includes a start time setting register 21, a saveregister 22 (data memory circuit), a multiplication/division register(frequency determination part), an oscillation control register 24, astart time buffer 25, a timer 26, an operation clock generation circuit27 (frequency determination part) and an oscillator circuit 28. Thestart time setting register 21 is operable when the standby powervoltage VOS5 is being supplied. The start time buffer 25 is operablewhen the standby power voltage VO3 is being supplied. The registers 21to 24 are connected through the communication circuit 8 and a bus 29.

The start time setting register 21 and the multiplication/divisionregister 23 are written and set with predetermined data, which aretransmitted from the host computer 6 through the communication circuit8, respectively. The data written in the start time setting register 21and the multiplication/division register 23 are forwarded to the starttime buffer 25 and the operation clock generator circuit 27,respectively, after the standby power voltage VOS3 is supplied. Theoscillation control register 24 makes the oscillation enable signal OEapplied to the oscillator circuit 28 active (high) by writing apredetermined value (for example, 1) as an activation command for thetimer 26 by the host computer 6 through the communication circuit 8. Theoscillation control register 24 makes the oscillation enable signal OEinactive by writing a different predetermined value (for example, 0) asa stop command for the timer 26.

Data are forwarded between the save register 22 and the timer 26. Thehost computer 6 is configured to retrieve the data, which is stored inthe save register 22, through the communication circuit 8 whennecessary.

A clock signal, which is generated by the oscillator circuit 28 at afrequency of, for example, about several MHz, is inputted to the timer26 through the operation clock generator circuit 27. The operation clockgenerator circuit 27 is formed of a PLL (phase-locked loop) circuit andthe like to output an operation clock signal to the timer 26 aftermultiplying or dividing the clock signal in accordance with amultiplication/division data written in the multiplication/divisionregister 23.

The timer 26 performs a count-up operation by the operation clocksignal. The timer 26 has a built-in comparator (not shown), whichcompares the time data measured by itself with the start time stored inthe start time setting buffer 25. When both of the data agree, a highlevel signal (coincidence signal) is outputted to the OR gate 13 throughthe level shift circuit 30. When the measured time reaches a maximumcount (full count), the timer 26 outputs a maximum count signal MC tothe oscillation control register 24. The oscillation control register 24is cleared from the set state and makes the oscillation enable signal OEinactive.

The communication circuit 8 directly outputs a clear signal CL to thesave register 22 and the timer 26 in response to a command transmittedfrom the host computer 6. Receiving the clear signal CL, the measuredtime data stored in the save register 22 is cleared, that is, changed tozero (0) and the data measured by the timer 26 is cleared to zero. Inthe configuration shown in FIG. 3, when a signal is transmitted betweenone block supplied with the standby power voltage VOS5 and the otherblock supplied with the standby power voltage VOS3, the signal level isappropriately shifted by the level shift circuit as described abovealthough not shown.

An operation of the present embodiment will be described next withreference to FIG. 4 to FIG. 6. FIG. 4 shows processing (both hardwareand software) executed by the ECU 1 when the IGSW 4 is turned on by apassenger of the vehicle. FIG. 5 shows processing executed by the ECU 1when the IGSW 4 is turned off FIG. 6 shows signal changes produced bythe processing of FIG. 4 and FIG. 5.

When the IGSW 4 is turned on as shown by (a) in FIG. 6, the gate of theN-channel MOSFET 14 is raised to high level through the OR gate 13. TheN-channel MOSFET 14 is turned on to supply the battery voltage to thecoil 3L of the main relay 3. The normally-open contact 3C is closed andthe power voltage +B is supplied to the power circuit 5 (S1 in FIG. 4and (b) in FIG. 6). The power circuit 5 thus starts supply of the mainpower voltage VOM5 (S2 in FIG. 4 and (c) in FIG. 6). Although notdescribed in detail, the main power voltage VOM1 for the core of thehost computer 6 is also supplied at the same time as the main powervoltage VOM5.

Immediately after supply of the main power voltage VOM5 is started, theVOS3 regulator part 19 is still stopped (S3: NO). When the voltage ofthe main power voltage VOM5 rises and reaches the reference voltageVREF, the output terminal of the comparator in the VOS3 regulatorcircuit 10 becomes high (S4: YES). The enable signal is applied to thebandgap circuit 17 and the VOS3 regulator 18 through the OR gate 16thereby to activate the bandgap circuit 17 and the VOS3 regulator 18(S5).

In the soak timer circuit 11, the tinier value saved in the saveregister 22 is restored (loaded) to the timer 26. The start time setvalue, which has been set in the start time setting register 21, iscopied to the start time buffer 25. The multiplication/division setvalue, which has been written in the multiplication/division register23, is set in the operation clock generator circuit 27 (S6). The setvalue may be identified as the multiplication value or the divisionvalue by previously setting predetermined different value ranges for themultiplication value and the division value, respectively.

When the host computer 6 outputs the oscillation start command (S7: YESand (e) in FIG. 6) by writing the predetermined value in the oscillationcontrol register 24 from the host computer 6 though the communicationcircuit 8, the oscillator circuit 28 is activated and starts itsoscillation operation (S8 and (f) in FIG. 6) and the tinier 26 startstime measuring (count-up) operation (S9 and (g) in FIG. 6). It is notedthat the timer 26 continues the time measurement operation even in theon-period of the IGSW 4 thereby to check whether the timer 26 isoperable normally.

Referring to FIG. 5 next, when the IGSW 4 is turned off ((a) in FIG. 6),it is checked whether the start time setting register 21 is written withdata that is, the start time set value is updated, by the host computer6. If it is updated (S11: YES), the updated data is copied to the starttime buffer 25 (S12). When the host computer 6 commands outputting ofthe clear signal (S13: YES), the communication circuit 8 outputs theclear signal to clear the timer 26 and the save register 22 (S14).

The host computer 6 causes the gate of the N-channel MOSFET 14 throughthe OR gate 13 to shut off power supply to the coil 3L of the main relay3 and open the relay contact 3C. As a result, since the voltage of thepower voltage +B falls (S15 and ((b) in FIG. 6), the power circuit 5stops outputting the power voltage VOM5 (S16 and (c) in FIG. 6). As longas the oscillator circuit 28 continues its oscillation operation (S17:YES) thereafter, the timer 26 continues to perform the count-upoperation (S18 and (g) in FIG. 6).

In this operation, the time measurement data of the timer 26, that is,the measured time, is copied (forwarded) to the save register 22 eachtime the data is incremented by the count-up operation S(19). That is,the timer 26 and the save register 22 are configured to operate asdescribed above. For example, after the time measurement data of thetimer 26 is forwarded to the save register 22 for the first time, thesaved data in the save register 22 is counted up by the same clock asthe operation clock of the timer 26.

Until the measured time (timer value) of the timer 26 reaches the starttime stored in the start time buffer 25 (S21: NO), step S18 is executedto repeat the count-up operation. When the measured time reaches thestart time (S21: YES), the timer 26 outputs the coincidence signal. TheN-channel MOSFET 14 is responsively turned on to supply power voltage tothe coil 3L of the relay 3 and close the relay contact 3C. The powervoltage +B is supplied to the power circuit 5 (S22). As a result, themain power voltage VOM5 is supplied and the host computer 6 starts tooperate. The measured time, in which the timer 26 starts its countoperation at step S18 until the count reaches the set start time, is thesoak time.

The host computer 6, when started, performs a predetermined operation(for example, heat management control or EVP leak check), which is to beperformed during the off period of the IGSW 4. Then, the power supply tothe coil 3L is shut off to open the relay contact 3C, and remains in thestandby state again ((b) and (c) in FIG. 6). When the timer 26 continuesits count operation and its count reaches the maximum count (S20; YESand (g) in FIG. 6), a maximum count signal MC is outputted. As a result,the oscillator circuit 38 stops its oscillation operation (S23 and (f)in FIG. 6) and the internal power circuit 20 stops its operation (S24and (d) in FIG. 6).

According to the present embodiment described above, the standby powervoltage VOS3 is generated by lowering the battery voltage BATT, which issupplied always from the external side, that is, continuously even whenthe IGSW 4 is being turned off. The main relay 3 is turned off to shutoff the supply of the power voltage +B. While the timer 26 continues thetime measurement operation in the standby state, the measured time dataof the timer 26 is saved in the save register 22. When a stop conditionfor stopping the time measurement operation of the timer 26 issatisfied, the control circuit 19 (FIG. 2A) in the VOS3 regulatorcircuit 10 stops the operation of the internal power circuit 20 (FIG.2A) in the VOS3 regulator circuit 10. When the main relay 3 is turnedon, the control circuit 19 starts the operation of the internal powercircuit 20. The measured time data saved in the save register 22 isrestored to the timer 26.

Since the standby power voltage VOS3 need not be supplied while thetimer 26 does not perform its time measuring operation, powerconsumption is reduced by stopping the operation of the internal powercircuit 20. Although the internal power circuit 20 is stopped fromoperating, the measured time data of the timer 26 is saved in the saveregister 22. When the main relay 3 is turned on, the internal powercircuit 20 is started to operate and the saved time data is restored tothe timer 26. The timer 26 is thus enabled to continue the timemeasurement operation, which has been stopped at the time of previousshut-off of the supply of the standby power voltage VOS3. As a result,even if the internal power circuit 20 need be provided to enable thetimer 26 to operate in the standby state, it is possible to suppress anincrease in the power consumption.

The measured time data is saved in the save register 22 at everycount-up operation of the timer 26. As a result, even if the measuredtime data is not saved at the time of satisfaction of the stop conditionof the time measuring operation of the timer 26, the latest measuredtime data can be maintained in the save register 22. The timemeasurement stop condition is set to a state, in which count of thetimer 26 reaches the maximum count. That is, in the configuration thatthe host computer 6 is started to operate when the measured time of thetimer 26 reaches the start time, it is not necessary to continue thetime measurement operation after the count of the timer 26 reaches themaximum count. By thus stopping unnecessary time measurement operation,the power consumption is suppressed from increasing.

The start time of the host computer 6, which operates with the mainpower voltage VOM5, is set in the start time setting register 21. Therelay control circuit 9 turns on the main relay 3 to start the hostcomputer 6, when the measured time of the timer 26 agrees to the setstart time. In this case, the set start time is transmitted from thehost computer 6 and set in the start time setting register 21 throughthe communication circuit 8. Thus the host computer 6 can set in thestart time setting register 21 the time period, which starts from a timepoint when the main relay 3 is turned off to stop its operation to atime point when it is started next time by the relay control circuit 9.The start time can be set arbitrarily in accordance with controlcontents to be performed. In this case, the standby power voltage VOS5is supplied to the start time setting register 21. As a result, evenwhen the supply of the standby power voltage VOS3 is shut off and theoperation of the timer 26 is stopped, the data of the start time can bemaintained.

Further, since the host computer 6 is configured to output the startcommand and the stop command for the timer 26 through the communicationcircuit 8, the host computer 6 can arbitrarily set the period of timemeasurement operation of the timer 26. In addition, since the hostcomputer 6 sets also the frequency of the operation clock, which issupplied to the timer 26, through the communication circuit 8, the hostcomputer 6 can arbitrarily set a resolving power of the time measurementoperation of the timer 26 in accordance with objects for timemeasurement. The host computer 6 also outputs the clear command for thetimer 26 through the communication circuit 8. The host computer 6therefore can clear the timer 26 at an arbitrary time point inaccordance with its control contents.

When the host computer 6 controls the engine of the vehicle as the ECU1, it can start its control if necessary by activating by itself evenduring the turn-off period of the main relay 3. Further it can cause thetimer 26 to perform the time measuring operation even during otherperiod so that the measured time may be used in engine control. Sincethe main relay 3 is turned on and off in response to the IGSW 4, themain relay 3 is turned off when the IGSW 4 is turned off. It is thuspossible that the host computer 6 performs required control while thevehicle is stopped. In addition, since the relay control IC 7 isintegrated into a semiconductor circuit chip, the entire size can bereduced.

The electronic control device is not limited to only the embodimentdescribed above and shown in the drawings but may be modified asfollows.

Although plural power voltages corresponding to the first to the thirdpower voltages are needed, the types and supply voltages of other powervoltages may be determined individually.

The multiplication/division register 23 may be provided as the case maybe.

The time point of saving the measured time data of the timer 26 to thesave register 22 need not be performed at every count-up of the timer 26but may be performed only once just before the operation of the internalpower circuit 20 is stopped.

The start command, the stop command and the clear command for the timer26, which are applied from the host computer 6 through the communicationcircuit 8, may be applied differently.

The host computer 6 and the relay control IC 7 may be connected by anaddress bus and a data bus and integrated into a single integratedcircuit thereby to eliminate the communication circuit 8.

The operation stop condition of the timer 26 is not limited to themaximum count but may be set to a predetermined count. Further, it isnot limited to a count value but may be set to other parameter inaccordance with individual design. The relay control IC 7 need not beprovided as a semiconductor integrated circuit but may be formed bydiscrete components.

The electronic control device is not limited to the system, whichcontrols the engine of a vehicle. The power switch is thus not limitedto such a switch, which is turned on and off in response to the ignitionswitch.

What is claimed is:
 1. An electronic control device comprising: aninternal power circuit, which is supplied with a first power voltagealways from an external side and a second power voltage through a powerswitch from the external side and generates a third power voltage bylowering the first power voltage; a control circuit, which controls anoperation of the internal power circuit; a timer, which is supplied withthe third power voltage and measures at least a time period of turn-offof the power switch; and a data memory circuit, which is supplied withthe first power voltage and stores data, wherein while the timerperforms a time measuring operation after the power switch is turnedoff, the data memory circuit saves therein a measured time data of thetimer, when a stop condition for stopping the time measuring operationof the timer is satisfied, the control circuit stops an operation of theinternal power circuit, and when the power switch is turned on, thecontrol circuit starts the operation of the internal power circuit torestore the measured time data saved in the data memory circuit to thetimer.
 2. The electronic control device according to claim 1, wherein:the data memory circuit saves the measured time data at every count-upof the timer.
 3. The electronic control device according to claim 1,wherein: the control circuit stops the operation of the internal powercircuit when a count of the timer reaches a maximum count.
 4. Theelectronic control device according to claim 1, further comprising: acommunication circuit, which is connected to a high level control deviceoperable with the second power voltage and communicates with the highlevel control device; a start time setting register, which sets a starttime provided by the high level control device through the communicationcircuit; and an activation circuit, which turns on the power switch whenthe measured time of the timer reaches the start time set in the starttime setting register.
 5. The electronic control device according toclaim 4, wherein: the communication circuit transmits a start commandand a stop command for the timer from the high level control device. 6.The electronic control device according to claim 4, further comprising:a frequency setting part, which sets a frequency of an operation clocksupplied to the timer, the frequency being set by the high level controldevice and transmitted through the communication circuit.
 7. Theelectronic control device according to claim 4, wherein: thecommunication circuit transmits a clear command provided by the highlevel control device to the timer and the save register to stop the timemeasuring operation and clear the measured time data.
 8. The electroniccontrol device according to claim 4, wherein: the start time settingregister is supplied with the first power voltage.
 9. The electroniccontrol device according to claim 4, wherein: the measured time data isused by the high level control device to control an engine of a vehicle.10. The electronic control device according to claim 1, wherein: thepower switch is turned on and off in response to an ignition switch of avehicle.
 11. The electronic control device according to claim 1,wherein: the internal power circuit, the control circuit, the timer andthe data memory circuit are integrated in a single semiconductorcircuit.